Boring TB after work - any tips?

Well, for a variety of reasons (money) I'm inclined to bore my own TB after work today.
It looks like aluminum / something soft enough to grind out with a dremel and a few rough sanding wheels.
I'll then go over it with something a little finer, then something really fine.
After that, I'll run it through the parts washer so my engine doesn't inhale metal dust.

Thoughts? Cautionary tales? Advice of any sort?

Are you going to just take out the step below the butterfly ? Or open it up bigger ? If bigger you will need to make a new butterfly blade--doh.

I noticed little to no gain when it was bored out,other than a whistle at 3 grand.After running it for several months I put the stock unit back on.

Wayne

I tried a Dremel, but without any luck. Picked up a cheap drum sanding kit (3 abrasives, ~2" rubber wheel, drill arbor) and that did it easily. The larger the drum, the easier it is to keep the cut away area round, IMO. I painted the bottom, scored the new diameter in the paint, and ground to the line. I used some tape on the drum and inside the throttle body as a reference, so I wouldn't grind far enough to affect how the plate seats inside the TB. A little trial and error was required to keep the IAC port from whistling.

Only pic I have of the sander I used. Chucked it in my old corded drill, clamped the TB to the bench, and went after it.



Used the drums until I had the taper removed and as smooth as I could, and used some finer paper to get it smooth again. Not quite as nice as the stock bore, but i can't imagine it's an issue, considering what the inside of the manifold looks like.


Yow, giant pictures. I need to resize them.

I did the same but used a drill press with the barrel sanders in it. It was really smooth peddle response but the whistle aggravated me too much. I think there is a way to get rid of the whistle I just can't remember how.

round off any sharp edges, IE bottom of TB, where air enters the sensor area, etc.

reduce the sharp edges and that 'should' be rid of the whistle

YOu need to chanfer that edge again.. A large one like what was there before.. I opend my TB up to 60 mm before having to make a new butterfly.. And BTW the fly is not perfectly round.

A better way of doing the sanding drum method is to hold onto the TB and turn it slowly with a drill or whatever. However you can hold onto it. Then use a drill at higher speed with the drum. This will help and keep it round. this is how my machines at work operate.. I can hold .00005 on those manual machines.. Guy i work with can split that in half in 1/3 the time it took me.. He is good..

That little area outside the circle is what I did to mine to cure the part throttle whistle- if you look at a stock TB, it has a similar notch cut into the taper. Removing the taper removed that notch on mine, so I made a slightly smaller notch in the same shape.

If you have access to proper machinery for this kind of thing, you'd be a fool not to use it- but if you're on a budget, and not a machinist, it's not difficult with a $5 drum sander.

What I'm picking up on is "drum sander"
I'll go buy one soon, chuck it up in the drill press at work and do this mod later.
Thanks, all!

I used my dremel. Didn't get a whistling noise either.